Wang Peiwen,Hu Eming,Wang Qingliang,Lei Zhiwu,Wang Hongqiang,Zhang Yan,Hou Wei,Zhang Rui
Both uranium and beryllium are very important strategic metals and have been applied to many fields, such as nuclear industries, atomic energy, metallurgical industries and telecommunications industries. When uranium and beryllium in the ore were leached simultaneously, a complicated downstream separation process was needed. Based on the different chemical stabilities of uranium and beryllium, an acid leaching method was employed in this work to selectively extract uranium from uranium–beryllium ore. The effects of sulfuric acid concentration, temperature, liquid–solid ratio and leaching time on the leaching efficiency were studied experimentally. Results indicated that treatment of the ores in 0.2 M sulfuric acid at 348.5 K for 50 min with the solid–liquid ratio of 0.25 g/mL is optimum. Under optimal conditions, the leaching efficiencies of uranium is 97.4% and the leaching efficiencies of beryllium is 1.78%, and the standard deviation of them are less than 2% and 0.06%, respectively. Results of kinetic study suggest that the leaching process of uranium was thermodynamically favorable and was controlled by the diffusion of the product layer, whereas the rate-determining step for beryllium leaching is the surface chemical reaction.
Wenbo Wang,Wenkai Dong,Guangyan Tian,Luyi Sun,Qin Wang,Aiping Hui,Bin Mu,Aiqin Wang
A simple one-step hydrothermal acid-leaching process was employed to efficiently convert natural Pal to porous silica nanorods with a high SiO 2 content and decent length of nanorods. At a lower acid concentration (2.0 mol/L), silica nanorods with the SiO 2 content of 97.84% and a rod length equal to original length of Pal nanorods were obtained by this process; while only the products with lower SiO 2 content of 79.92% were obtained by a normal acid-bleaching process. Although increasing acid concentration to 8.0 mol/L may enhance SiO 2 content to 94.56% in normal acid-leaching process, which led to sharp reduction of length of nanorod. The synthesized porous silica nanorods have a specific surface area of 119.39 m 2 /g, average pore size of 7.56 nm, and better whiteness (the L *, a * and b * values are 86.130, 0.131 and 2.801, respectively). This paper provided an effective, universal approach to produce silica nanomaterials from diverse natural clay minerals.
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